Nick_M
New Member
Posts:5
 |
| 20 Mar 2012 01:02 AM |
|
Anyone know if one type of PVC piping is better for radon mitigation systems - solid core or cellular core? This will be a 4" Schedule 40 PVC pipe ran up through the interior conditioned walls. Initially it is being designed as passive radon mitigation system but is planned to allow conversion to active by adding a fan if test results come back above acceptable levels. Wasn't sure if one would be better from a permiability standpoint or a noise standpoint if the system does have to be converted to active in the future. |
|
|
|
|
|
|
ICFHybrid
Veteran Member
Posts:3039
|
| 20 Mar 2012 09:15 AM |
|
Polymer films a few mils thick are effective radon barriers. There is going to be no appreciable difference between solid or cellular core PVC for that purpose. |
|
|
|
|
Alton
Veteran Member
Posts:2164
|
| 20 Mar 2012 11:04 AM |
|
My limited knowledge is based on what I have seen installed.
My guess is that it may cost less to use schedule 40 than cellular PVC. The systems that I have seen have pipes buried in clean gravel under the slab. These pipes have many holes that allow the radon gas to enter. Since schedule 40 PVC is used for plumbing waste lines, I think it is strong enough to resist crushing. The pipes in the walls up through the roof are solid pipes. The fan is usually located in the attic where it is accessible for repairs and where it will pull air into the pipes under the slab. |
|
Residential Designer &
Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period .
334 826-3979 |
|
|
jonr
Senior Member
Posts:5341
|
| 20 Mar 2012 06:13 PM |
|
These things seem like a step backwards energy wise. Pull air from and through the house and then dump it outside.
|
|
|
|
|
Lee Dodge
Advanced Member
Posts:714
|
| 20 Mar 2012 07:07 PM |
|
jonr-
Radon remediation systems should be pulling air from under the foundation or crawl space and venting it to the outside, not pulling conditioned air out of the house. The one in my house operates like Alton described. 4" perforated PVC pipe is buried in the gravel at the base of the crawl space, and that gravel is covered by a layer of plastic that is sealed to the crawl space walls. My system has two of these 4" perforated pipes running parallel to each other and along the long axis of the crawl space. These two pipes are independently connected to the vertical pipes, but they are reduced to 2" (non-perforated) pipes so that they could be fed up through 2"x4" studs. (The EPA recommends 3" or preferably 4" vertical pipes.) The passive system did not quite meet the radon spec. of 4.0 (units?), so I added a small fan to each of the two independent piping systems, and that brought the level well under the spec. |
|
Lee Dodge,
<a href="http://www.ResidentialEnergyLaboratory.com">Residential Energy Laboratory,</a>
in a net-zero source energy modified production house
|
|
|
jonr
Senior Member
Posts:5341
|
| 20 Mar 2012 09:53 PM |
|
Radon remediation systems should be pulling air from under the foundation or crawl space and venting it to the outside, not pulling conditioned air out of the house. In most cases I have seen it is pulling air from under a basement slab and the source of this air is the basement (if not, then where?). Then the air gets warmed up traveling through the house in an uninsulated PVC pipe. Would be interesting to measure the temperature and flow (ideally quite low) to know how much energy is being lost.
See Figures 9 and 18 - http://www.aarst.org/proceedings/2009/ENERGY_LOSSES_AND_OPERATIONAL_COSTS_OF_RADON_MITIGATION_SYSTEMS.pdf
$300/year, more than I spend on hot water? |
|
|
|
|
Lee Dodge
Advanced Member
Posts:714
|
| 20 Mar 2012 11:39 PM |
|
Posted By jonr on 20 Mar 2012 09:53 PM
Radon remediation systems should be pulling air from under the foundation or crawl space and venting it to the outside, not pulling conditioned air out of the house.
In most cases I have seen it is pulling air from under a basement slab and the source of this air is the basement (if not, then where?). Then the air gets warmed up traveling through the house in an uninsulated PVC pipe. Would be interesting to measure the temperature and flow (ideally quite low) to know how much energy is being lost.
See Figures 9 and 18 - http://www.aarst.org/proceedings/2009/ENERGY_LOSSES_AND_OPERATIONAL_COSTS_OF_RADON_MITIGATION_SYSTEMS.pdf
$300/year, more than I spend on hot water? That is an interesting reference, although I only skimmed the paper. When you say where else does the air come from other than the basement, some of the air comes from the air permeability of the soil ( http://www.surechem.com.my/download...P1-88e.pdf). I am guessing from the note under figure 9 "Ventilator: 150 W ventilator, 120 cfm, Internal losses: 60 cfm" that they are assuming 1/2 of the air is coming from the soil and half from the basement. It looks like they estimate that a radon remediation system in Ft. Collins running at 150 cfm would waste about $350 a year if the basement were not carefully sealed. We have more degree days here than in Ft. Collins, higher altitude, there are two small fans in the radon system, and the total annual natural gas bill for heating, hot water, and cooking is under $300. The radon levels measured with the fans running was about 1.3 pCi/L, although it was around 9 pCi/L without the fans operating. In addition to sealing the basement, the conclusion that I draw from this paper is to choose the smallest fan that allows for a radon level below the 4 pCi/L standard by whatever margin is desired. I purchased the lowest power consuming fans that were available from the supplier, although my radon levels were not nearly as high as for some houses. Maybe I'll test my system with just one fan running to see what the radon levels are. |
|
Lee Dodge,
<a href="http://www.ResidentialEnergyLaboratory.com">Residential Energy Laboratory,</a>
in a net-zero source energy modified production house
|
|
|
FBBP
Veteran Member
Posts:1215
|
| 21 Mar 2012 12:31 AM |
|
I think the riser pipe can be thin wall pipe just like the perf only not. Some folks tie it to the weepers and some add a inlet on the outside to the weepers. Now you use the thermal stack to draw outside air, under the slab to the roof. If you want to further negate heat loss, insulate the slab and put a insulated sleeve around the riser. For those unfamiliar with radon gas, this is a naturally occurring ground gas that is the result of decomposition of the underlying materials. This type of remediation is not required everywhere. |
|
|
|
|
ICFHybrid
Veteran Member
Posts:3039
|
| 21 Mar 2012 12:51 AM |
|
Maybe one could get one of those solar air heaters for the side of the house and heat the air before drawing it into one end of the radon removal system. During the cooling season, you could run it primarily at night to provide cooling down there. Maybe put a radon detector switch on it to satisfy code such that it runs whenever levels get too high. |
|
|
|
|
Lee Dodge
Advanced Member
Posts:714
|
| 21 Mar 2012 10:00 AM |
|
Posted By FBBP on 21 Mar 2012 12:31 AM
""
For those unfamiliar with radon gas, this is a naturally occurring ground gas that is the result of decomposition of the underlying materials. This type of remediation is not required everywhere. That is an excellent point. More specifically (from http://energy.cr.usgs.gov/radon/georadon/2.html), "Radon is a gas produced by the radioactive decay of the element radium. Radioactive decay is a natural, spontaneous process in which an atom of one element decays or breaks down to form another element by losing atomic particles (protons, neutrons, or electrons). When solid radium decays to form radon gas, it loses two protons and two neutrons. These two protons and two neutrons are called an alpha particle, which is a type of radiation. The elements that produce radiation are called radioactive. Radon itself is radioactive because it also decays, losing an alpha particle and forming the element polonium." "Elements that are naturally radioactive include uranium, thorium, carbon, and potassium, as well as radon and radium. Uranium is the first element in a long series of decay that produces radium and radon. Uranium is referred to as the parent element, and radium and radon are called daughters. Radium and radon also form daughter elements as they decay." So, radon is problem where uranium occurs. A map of radon levels by U.S. states is at http://www.radon.com/maps/. Radon is supposedly the second leading cause of lung cancer after smoking. There is no safe level of radon, but the EPA recommends action if the level is above 4.0 pCi/l. (Even at that level the statistics sound scary.) |
|
Lee Dodge,
<a href="http://www.ResidentialEnergyLaboratory.com">Residential Energy Laboratory,</a>
in a net-zero source energy modified production house
|
|
|
Lee Dodge
Advanced Member
Posts:714
|
| 21 Mar 2012 10:03 AM |
|
Posted By ICFHybrid on 21 Mar 2012 12:51 AM
...
Maybe put a radon detector switch on it to satisfy code such that it runs whenever levels get too high. The electronic radon detector that I used needed a measurement interval of two or three days, so it may not be possible to use that type of sensor in a control loop. |
|
Lee Dodge,
<a href="http://www.ResidentialEnergyLaboratory.com">Residential Energy Laboratory,</a>
in a net-zero source energy modified production house
|
|
|
jonr
Senior Member
Posts:5341
|
| 21 Mar 2012 10:14 AM |
|
Even at that level the statistics sound scary.) Agreed - there is no "safe" radon level, it all contributes to cancer. I understand that it is highly synergistic with smoking (ie, the combination is very bad). I doubt that 6 ft of soil is very permeable to air, but I don't have figures. Maybe gravel backfill is. Agreed, in a well sealed basement (floor vapor barrier + foam), the flow (and heat loss) could be low. |
|
|
|
|